Climatology - Lecture notes 4 - 7 PDF

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Climatology notes and general descriptions covered in climate section of EGS...

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What Climatology Is: Climatology, or sometimes known as climate science, is the study of the Earth's weather patterns and the systems that cause them. From the ocean oscillations to trade winds, pressure systems that drives temperature, airborne particles that influence local conditions and even the phases of the moon and Earth's wobble all affect the climate !(1)!. The word “climatology” comes, as may scientific words and terms do, from the Greek. !Klima!means “zone” or “area” and “logia” means “study”. This means that climatology is the “study of zones” although in reality it is much more complicated than that. Climatologists! today are almost universally directing their efforts toward explaining and attempting to do something about global warming, but a the list below, that is not the science's only puzzle to solve nor the limits (2)!. Until relatively recently, it was considered a dry and uninteresting, y area of science. But since it became clear that human actions are dama environment and changing the climate, it has become much more prom and internationally with most government departments in most countrie responsibilities to mitigate or prepare for !climate change! scenario.

What Climatology Is Not Climatology is not m ! eteorology!; both concern weather patterns and the ff t b t diff i lth h th ill b i t t di h

drought patterns, and their long-term, long-range impact on various top globally. ● Meteorology is what the weather is doing now whereas clima you expect to see !(1) ● Meteorology is short-term effects and results, climatology is lo consequences ● Meteorology concerns small areas; climatology concerns mu or global results Even how they use equipment differs. Satellites, for example, are used to track weather systems and to monitor atmospheric fronts to predict w will do next. Climatologists use different data sets from satellites - temp various levels through the atmosphere and at ground level, for example energy flows and noticing changes that could affect local climate !(2)!.

Natural Variables That Influence Our Oscillations Much of the discussion of climatology in public discourse concerns anth climate change - the contribution of human activity to such events as ca greenhouse gases, and their effects such as the Greenhouse Effect an bleaching. But climatology is not just about the human impact, it is abou predicting the effects of the natural processes on our planet and the So to long-term trends, long-term and large-scale processes to which we d in understanding why the climate looks or acts the way it does, and wha anomalies can potentially change it. Here are some of the natural trend

They are usually predictable, but the increasing effects of climate chang sometimes push them back to a little later. Known as ENSO, they are o the same process and are defined as an oscillation (a variation in magn the temperature of the atmosphere and the ocean. In this case, ENSO eastern equatorial Pacific. Geographically speaking, it approximates to between the International Dateline and 120 degrees west of there. El N arrives between June and December in a given year and takes place w and failure of replacement of the Pacific Trade Winds following the Pac season. The warm air then creates this oscillation and the waters becom La Niña occurs when the situation is reversed; it usually follows El Niño Here, trade winds are stronger than normal, moving warm water westw Pacific. The east of the ocean is colder than normal while the west is w average. But the effects don't just affect the Pacific, they are global.

The Effects of ENSO The biggest impacts are felt in the Pacific area in the immediate and sh

from August to November, the tip of South America tends to have highe while tropical Africa is drier than normal. But precipitation is not the only Northern Europe tends to be much colder in the winter months while ce western Europe will experience warmer than normal temperatures in th see maps)!. Here in the US, the Eastern Seaboard will experience lowe between December and May while the same area will experience colde between June and September - the height of the summer months. With La Niña!, these effects will tend to be flipped !(5 - see maps)!. Cent the southern US can expect lower precipitation between the following D March while the opposite is true just a few thousand miles to the south of South America. In fact, most of the central tropics from Africa through Ocean to the western Pacific will experience higher than average rainfa

Madden-Julian Oscillation Not as well known as ENSO, the Madden-Julian Oscillation (MJO), it fu differently !(6)!. While ENSO is static, occurring in one place due to the c create those conditions, MJO moves across a geographical area - eastw tropics, bringing higher levels of cloud, increased precipitation and there rainfall. It returns to its starting position anything between one and two began. It can be tracked and was only identified in the 1970s. There ma events in a single place since it moves. It also experiences variable spe conditions ahead, during, and behind it. With each event, there is an inc event and a suppressed rainfall event. Why is it important? Tropical weather events are predictable once MJO this means preparing for extreme weather (potential drought and floodin areas. But it can have much longer range effects, creating knock-on eff as the northern US, Canada, and northern Europe !(7)!. This is why wea the northern hemisphere are increasingly interested in incorporating its monitoring and prediction services. North Atlantic Oscillation

between these two points, the westerly winds direction and strength cha also affects the strength, frequency and direction of Atlantic storms. It h since the 19t! h! century, and unlike some of the others discussed in this s mostly atmospheric, affected and part of the Arctic Oscillations. It is a natural oscillation and can massively impact the continents on eit North America and Europe. When one side has certain conditions, the o opposite conditions. It will also affect the North Atlantic Jet Stream whic Europe and North America temperate compared to adjacent areas. Positive NAO! is when warm westerly winds dominate the North Atlanti air from the southern US coastal states northeast towards northwestern British Isles, for example, tend to experience warm but wet weather. Ho direction means colder weather in the northern coastal states and Cana Atlantic side and southwestern Europe. Negative NAO !also carries weather fronts from North America to Weste this case, the southern US states experience cold and snowy weather c their northern counterparts experience warmer weather. In Europe, Sca to be cold but dry while the Mediterranean Basin is warmer and wetter.

North Pacific Oscillation The North Pacific Oscillation works similarly to the North Atlantic Oscilla system divided by northern and southern regions. Also, like the NAO, th phases. The first is the Aleutian Below (south of the Aleutian Islands), t Aleutian Above (north of the islands). They create variable weather patt on which is currently in progress. It's not a well-known oscillation as far concerned, but its impacts are far greater than the NAO and ENSO. It r Alaska to Hawaii !(9)!. During the “above” phase (known as the deeper Aleutian low), the Nort continent is warmer except for certain areas of the western US with hig precipitation over the Pacific Northwest. There is also impact on sea ice

Similar to the ENSO, the PDO occurs over much longer timeframes - m decades, hence the name. Typically, the phase lasts for around 20 or 3 compared to ENSO which lasts no more than six years (incorporating b La Niña). It also incorporates both a warm and a cool period during the of which impact upper atmospheric winds !(10)!. Despite its geographic l impact global weather and climate, including frequency and intensity of across the Pacific and even in the Atlantic. Sometimes, hurricanes in th and into Europe are a result of what happened in the Pacific, impacting and drought effects. Land temperatures and marine ecosystems are aff former being increased while the latter's production of plankton reduces wider ecosystem. It also has an interesting relationship with ENSO. Wh together, impacts are magnified but when they are out of phase, it appe effectively mitigated.

Interdecadal Pacific Oscillation The Interdecadal Pacific Oscillation (IPO) is similar to the PDO but it co the Pacific area south of the PDO (south of the 20 degrees N latitude), anything from 15 to 30 years !(11)!. When the IPO is positive, temperatu the Pacific tropical and subtropical areas but warmer farther to the north PDO, it can have amplification or mitigation effects in conjunction with E particular and noteworthy differences to the climate of Australia, New Z seas around those countries.

Other Natural Climate Drivers The oscillations are just some of the natural forcings on the climate. Th anthropogenic forcings too which are discussed in the next section, but interactions are not the only naturally-occurring events.

Sun Activity At the center of our solar system is a star that we call “The Sun”. The su constant stream of energy produced by !nuclear processes! that generat amount of heat, light, and radiation. This radiation hits the atmosphere by the ozone layer which reduces the most harmful. The resulting heat rays that do make it to the surface enable all life on the planet from the the !chemical! processes to reproduce through photosynthesis which, in animals. But the sun's energy is not constant. The temperature and the levels fluctuate and that can have a knock-on effect for the Earth. It see was responsible for two climate events that took place less than 1,000 y Little Ice Age and the Medieval Warm Period! !(17)!. The decrease in sola certainly contributed to the LIA, but it was by no means the only factor (see below for further details) also impacted global temperatures - there the Little Ice Age. The Medieval Warm Period (MWP) certainly correlate increase in solar activity and a decrease in volcanic activity during the p As atmospheric particles increase, so does air density. This leads to the effect. Less heat is reflected back into space and more is absorbed in t atmosphere. This is what happened on the planet Venus which has den and a runaway Greenhouse Effect !(12)!. Mars atmosphere is too thin; w happens, too much heat escape, leading to the opposite effect.

Volcanoes These are immense s! eismologica!l events that can cause short-term we and, when enough events have accumulated or are particularly large, lo effects. It is largely believed that the explosion of the Thera (Santorini) v antiquity led to the collapse of several complex societies !(19)!, not just t civilization that inhabited the island at the time, but also deeply affected too and led to the downfall of the Minoan civilization which, just a few ye conquered by the Mycenaeans. Writings about the event are found all o

The Little Ice Age created a brief yet intense change to the northern he climate. This was a period of unusually high volcanic activity !(18)! but ev whether this was a cause is still limited and subject to much speculation know that volcanic activity has an impact - mostly small, but sometimes lot together or there is a large enough single event, change occurs. In m times, Krakatoa in the East Indies cooled the planet's temperature rise level rise for at least two decades, and that was one volcano - albeit an (20)!.

The Human Impacts on Climate Of course, climatology is not just about the natural variations in the sho long term, it's primarily concerned today with the human impact on clim the various “forcings” that are already causing problems. Most of the fo have impacted the climate since the Industrial Revolution in the 19t! h! ce arguably started before that.

Greenhouse Gases Greenhouse gases are so-called because their abundance leads to a “g effect”. Greenhouses are glass buildings used to houseplants that requ shelter from the elements. By nature, they are warmer and more humid The effect on the global environment is similar. The greenhouse gases water vapor, nitrous oxide and carbon dioxide !(12)!. ● Water Vapor creates a feedback - precipitation and cloud cov leading to higher temperatures, but also creates more rainfal surfaces but can lead to flooding in some areas. ● Nitrous Oxide !(13)! is a byproduct of agricultural processes. It attention in the 1980s with so-called acid rain, but the reducti

proportionally high considering the low levels of the gas in the (14) ● Carbon dioxide is the best-known and most important of all g gases, it is released through several natural processes but al actions - one of the biggest impacting factors since the Indus (12) ● Chlorofluorocarbons (CFCs) are now heavily regulated since discovered how much their release was damaging the ozone level protecting the planet from the sun's most harmful rays

Deforestation Cutting down tree canopies without replacing it passively increases c! lim the simple fact that trees and other vegetation are carbon sinks !(15)!. Th we have, the faster carbon emissions will accumulate in the atmospher deforestation is increasing despite international efforts to slow it down a trees than we are cutting down. Some of this carbon is heading for the now absorbing much more carbon than it has done for a very long time to ocean acidification and coral bleaching which is upsetting the delicat marine ecosystems !(16)!, reducing ocean life that has come to rely on c survive.

A History of Climatology The Ancient Past to the Modern Age Many of the ancient precursors to modern science lived in Ancient Gree

was largely determined by the climate in which it lived - plants thrive wh “favorable place”.

Dawn of The Industrial Revolution Little is achieved over the nearly 2,000 years with naturalists and others comments and observations. True climatology - and an attempt to divid between the natural and the anthropogenic factors - arises to around th to understand how our m ! ining! for resources and increasing carbon emi the planet. It was during the 19t! h! century and the rush for p ! aleontologic paleobotanical fossils, a period in which humanity discovered the bones creatures such as dinosaur bones and megafauna from much more rec we began to understand the importance of e ! cology! and !geology! and im (22)!. The history of climate science/climatology is also, in many ways, a ecology and a history of paleoclimatology. These areas are intrinsically ways. Particularly, the idea that a climate could change quite dramatica revealed as once being a tropical swamp, the Arctic circle being more li than fields of ice, the retreat of sea levels and ice demonstrated quite c landscape can change dramatically. Ice Age Theory !(23)! developed thr evidence as research headed into the 19t! h! century and towards the Ind Revolution. Yet it remained, until the 20!th! century, a subdiscipline of meteorology, It height of the Industrial Revolution that chemists identified the greenhou above. Many of these were being pumped out by the thousands of tons the warming effects of CO2! ! emissions identified early on. At the time, it studying ancient changes to the planet including Jean-Pierre Perraudin mountain valleys and the boulders within them were created by ancient Initially mocked for such a suggestion, his theory soon gained traction.

The Later 19!th! Century Still, climate science remained a small section of meteorology but in 18

cooling, and more snow and ice coverage. The idea of global cooling b CO!2! levels didn't require much of a leap to presume the opposite could (26)!. In 1896, the first paper was published attempting to explain and discove increased atmospheric CO!2! !(27)!. V ! olcanoes! were an obvious choice, b knew the chemical composition of the coal being burned all over the de during the industrial revolution and knew that a byproduct of that burnin was the breakthrough that the young science of climatology had been w However, because emissions were relatively low, it was not seen as a n take thousands of years !(28)! - and would not until the turn of the centur scientists saw it as a good thing but that was without the understanding on ecology, biodiversity, the food cycle, sea levels, and long-term weath

Early 20!th! Century The first half of the century was one of fierce debate centering on the 1 discussed in the last section and the possibility that natural atmospheric caused the past ice ages that researchers had identified; we now know at least five of these !(29)!. Yet still, the evidence for paleoclimate stacke major area of focus for climate science. Studies in clay deposits across showed climate cycles; the evidence for a non-static climate was buildin in the 1920s and 1930s came up with the theory that the oceans could (28)!. Later decades would prove this right, but few understood the impl time. Around 1920, it was discovered that the “Solar Constant” was not true; climate could change through natural means was finally beginning to ta with evidence from the last century based on the fossil record (paleobo paleoclimate data and the anomalies of discovering marine remains in d demonstrated finally that planetary systems were not constant !(30)!, tha always subject to change - our planet, as a living system, had undergon and catastrophic change and would likely do so again. That would take after the war years to examine using new techniques and technologies

In the 1960s, researchers began looking at the climate and ecology thro humanity's actions. The publication of Rachel Carson's !Silent Spring!led of some toxic chemicals, the birth of ecology and research into how and humanity's actions in industries and every-day life impacted the climate competing theories sprang up. Amongst them was the idea that we wer Ice Age - Global Cooling was posited and then dismissed and despite c modern critics of climate science, it never gained traction and remained for its brief life !(31)!. This is also the decade of the Greenhouse Effect a of multiple ice ages - including small and brief instances lasting anythin hundred to a couple of thousand years !(32)!. It is not difficult to see why researchers believed in Global Cooling as a very real threat, something ran away with but never lasted in academic literature. There was a sligh between 1945 and 1975 that may have fueled this briefly. Aerial pollution! became a big problem and the matter came to a head in Following the publication of Carson's book !Silent Spring!, President Joh announced the formation of the Environmental Protection Agency and t although neither would come into effect during his presidency. The Spa everyone realize that we inhabit just one planet !(33)!, that our resources should do what we must to protect the natural environment for future ge well as having ecological benefits such as reducing pollutants from wat to improve damage and risks to climate such as imposing a tax on lead (which was eventually phased out). Under Nixon's presidency, the Fede reorganized to look at ways of reducing pollution through its own action

The 1980s to the Turn of the Millennium By now, climatology was firmly in the ranks of anthropogenic causes of fluctuations in the climate. It was, and is, still concerned with the natura many researchers today still examine this aspect of climatology but typi evidence from this source is produced to demonstrate human activity a mitigating factor. The 1980s was a turning point in many ways. It saw cr in aerial pollution, the phasing out (in many countries) of leaded fuel in its eventual ban in 1996) (34) similarly with CFCs (35) which were dam

suggests an almost certain correlation between human activity and the (36)!.

Data that reinforced the relationship between ice cores from Greenland paleodata !(37) !showing sometimes catastrophic climate change over a was quite clear by 1990 that despite the natural changes to the planet's processes, the existing data ...